Method for facilitating the harvest of fruit

ABSTRACT

The harvest of fruit from bearing trees is facilitated by application of effective concentrations of pisothiocyanatophenylacetic acid.

firmed States Patent 1 1 ,853,533 Archer [45] Dec. 10,1974

[ METHOD FOR FACILITATING THE HARVEST 01F FRUIT Kristian et al.,Synthesis and Properties of Aromatic, [75] Inventor. Milton C. Archer,Ollvette, Mo. (1966) CA 67 NO- 21531 X (1967) OTHER PUBLICATIONS [73]Assignee: Monsanto Company, St. Louis, Mo.

[22] Filed: Nov. 119, 1973 Primary Examiner-Glennon H. Hollrah Attorney,Agent, or FirmArnold H. Cole; Donald W. [21] APPI' 417,340 Peterson;Neal E. Willis 52 us. or. 71/104, 260/454 51] Int. Cl AOln 9/18 [571ABSTRACT [58] Field of Search 71/ 104 The harvest f f uit f bearing{trees is f ilit t d by application of effective concentrations ofp-isothi- [56] References Cited ocyanatophenylacetic acid. FOREIGNPATENTS OR APPLICATIONS 168,087 2/1965 U.S.S.R 71/104 10 Clams N0Drawmgs METHOD FOR FACILITATING THE HARVEST OF FRUIT This inventionrelates to a method for facilitating the harvest of tree fruit. Moreparticularly, it is concerned with the provision of a novel chemicalagent which serves to accelerate or enhance the normal abscissionprocess in such fruit.

The commercial growing of edible tree fruit is a major internationalindustry. As expected, those engaged in this industry are concernedabout getting their product to the consumer in the most economicalmanner. Traditionally, the harvesting of fruit crops has beenaccomplished by hand picking. However, in recent years, shortages ofmanual laborers have become increasingly more frequent. Coupled withconstantly spiraling wages, such shortages have lent impetus to theinvestigation of alternative harvesting methods.

One result of this investigation has been the development and testing ofa wide variety of mechanical devices designed to reduce or limit theneed for manual efforts. Said devices have generally been vibrators orshakers which can be driven through the areas where the fruit-bearingtrees grow. They attach to the trunk, or to major branches, and areactuated to produce a vibratory motion which'either loosens the fruit orcauses it to fall to the ground. Certain of these mechanical devicesalso include means for catching or otherwise collecting the fruit as itfalls. Although several types of such devices are now being used, theynormally require pretreatment of the fruit with an abscission agent inorder to be effective, and they often present a problem by causingdamage to whole trees or parts thereof.

According to the present invention, the harvesting of tree fruit isfacilitated by applying thereto a chemical agent. Although the mode ofaction of the chemical on the fruit is not known with certainty, it isfound that the treated fruit are more loosely attached to the stem.Removal of such fruit from the tree is thus facilitated, and, indeed,the treated fruit often fall from the tree without the need for anexternal force, either manual or mechanical.

In practicing the present invention, the particular chemical agentemployed is p-isothiocyanatophenylacetic acid. The compound can beprepared by adding thiophosgene to the corresponding amino acid inaqueous hydrogen chloride as described in Chemical Abstracts, 67, 2l53lThe compound of this invention is most advantageously applied to thefruit-bearing plant by spraying. While such application will normally becarried out with ground-based equipment, aerial spray techniques can beempolyed in those instances where a particular crop or culturalpractices indicate economic feasibility.

For use in accordance with this invention, said compound may beformulated and applied as a liquid, a dust or a wettable powderfollowing procedures known to the art. The active ingredient is admixedwith a suitable inert material serving as a solvent, diluent ordispersant, after which such admixture is further diluted to a desiredvolume of spray. It will be understood that the composition to beapplied can also contain surfactants, wetting agents, emulsifiers,sticking agents or other types of adjuvants whose nature and functionhave longbeen recognized in the art.

The method of this invention can be conveniently employed in thetreatment of any fruit-bearing trees or plants. Representative ofthefruits for which harvest can be thus facilitated are the common tablefruit such as apples, plums and cherries, the citrus fruit such asoranges and lemons, along with others such as olives, grapes and nuts.It is particularly preferred to use the compound of the presentinvention as an aid in the harvesting procedures for the fruit of thenon-deciduous trees, citrus and olives.

The time of application will vary from a few days (e.g., 3-4) up toabout 2 weeks prior to the planned date of harvest. Specific selectionwithin this short range will be dependent upon the type and variety offruit being treated and upon the stage of fruit develop ment prior totreatment. These factors will also be considered in the determination ofthe rate of application. From a practical standpoint, the compound ofthis invention is applied in a spray concentration of from about to4,000 ppm. (parts per million) active ingredient in total spray volume.A desirable degree of harvest facilitation is not obtained at lesserconcentrations, while higher concentrations detract from economy and mayalso cause undesired. injury to leaves and- /or green fruit.Applications at concentrations of from 500 to 2,000 ppm. areparticularly preferred.

To illustrate the practice of the method of this invention, tests areconducted to determine the effect of p-isothiocyanatophenylacetic acidon various tree fruit. Branches selected for these tests are those whichcontain at least 20 pieces of fruit that are to be harvested within thefollowing 2 weeks. The fruit are sprayed with a formulation of theactive ingredient described herein, and a number of days aftertreatment, observations are made of the number of fruit which havefallen to the ground. Fruit which has not fallen is clipped from thebranch with the stem attached to the fruit, and measurement is made ofthe force in pounds required to remove the fruit from the stem on astraight pull. Apparatus for such measurements is described in PlantPhysiology, Volume 43, Part B, pages 156045760968). When the forcerequired to remove the fruit from the stem is too small to be measuredon such apparatus, it is designated as too loose to pull.

In these tests, observations are also made of any adverse effects on anyleaves or green fruit which may be present on the branches. The extentof plugging, the removal of a part of the peel or rind when the stem ispulled from the fruit, is similarly noted along with any otherindications of fruit injury. Although significant portions of most fruitcrops are used for processing into juices, concentrates and cannedsections, the remainder must be marketed as fresh fruit. While injuriessuch as rind pitting, burning or discoloration are not of real concernin the case of processed fruit, such undesirable changes in appearanceare detrimental to fresh fruit sales. In addition, injuries such asplugging or rind splitting cannot be accepted for either market sincethey generally lead to rapid fruit rot.

In the illustrative tests hereinafter presented, it should be understoodthat untreated control branches are selected in each instance, andcorresponding measurements and observations are made on the fruitthereof. The tests also included treatment of branches withcycloheximide, a known fruit abscission agent, at a rate which wouldnormally cause all treated fruit to drop or be too loose for ameasurement of pull force.

By noting those instances in which this known compound does notdemonstrate its expected activity, conclusions can be drawn as to thevalidity of a particular test due to the adverse effects of externalfactors. Some of these external factors include problems with thespraying apparatus which often leads to inadequate or non-uniformapplication, and rainfall within a few hours after application, whichmay wash off the chemical treatment.

EXAMPLE 1 Spray formulations for this test are prepared by mixing asmall quantity (0.5 or 1 gram) of p-isothiocyanatophenylacetic acid inacetone to a total volume of 100 or 200 ml. Then, 10 ml. of surfactantis added, followed by dilution with water to a total volume of 500 ml.The active ingredient in these formulations is thus present atconcentrations of 1,000 or 2,000 ppm., and sprays are applied tobranches of Valencia oranges. After 7 days, fruit is removed from thetest branches, and measurements of pull force are made for at least 10fruit from each branch. At a concentration of 1,000 ppm., an averagepull of 11.9 pounds is required with 30 percent plugging, while at 2,000ppm., the average pull is 18.1 pounds with 60 percent plugging. Theuntreated fruit on the control branch requires an average pull of 26.2pounds, and 90 percent plugging occurs. A few leaves drop from thetreated branches, and the fruit show some light burn.

EXAMPLE II In this test, spray formulations are prepared as describedabove at concentrations of 500, 1,000, 2,000 and 4,000 ppm., andapplications to branches containing Hamlin oranges are made at eachrate. After 6 days, the untreated fruit requires an average pull of 16.7pounds with 90 percent plugging. No loosening is noted at the two lowestconcentrations, while the treated fruit is too loose to pull at 2,000ppm. At the highest concentration, all of the treated fruit falls to theground before the observation date. Some leaf drop and fruit burn isnoted at the higher rates.

EXAMPLE III Concurrently with the test of Example 11, application at thenoted rates is also made on branches of the same variety of fruit about3-4 hours after treatment with a 3 X 10 molar concentration of 2, 3,5-triiodobenzoic acid. It has been reported that ethylene is desirablein the abscission zone of plants in order to accelerate the abscissionprocess. Since the triiodobenzoic acid has been found to inhibit thetransport of auxins within plants, and since auxins are antagonistic toethylene production, the pretreatment attempted to minimize auxininterference. After 6 days, the observations made of treated branchesindicate some loosening at 500 ppm., but no other changes from theresults without triiodobenzoic acid in the preceding Example. It shouldbe noted that a control branch which received only the pretreatmentshowed no loosening of the fruit.

EXAMPLE IV About 1 month after the tests of Examples 11 and III, thesmae variety of fruit is treated with p-isothiocyanatophenylacetic acidat rates of 100, 300, 500 and 700 ppm. After 7 days, the treated fruitshowed no loosening at any of the four rates, while the untreated fruitrequired an average pull of 13.1 pounds with 100 percent plugging.

At the same time, tests were also made at the above rates on fruit whichwere pretreated with 3 X 10 and 6 X 10 molar concentrations of 2, 3,S-triiodobenzoic acid. With the lower concentration of pretreatment, theaverage pull required is 9.6 pounds at ppm., 12.1 pounds at 300 ppm.,7.6 pounds at 500 ppm, and 4.5 pounds at 700 ppm. The two lowest ratesshowed 10 percent and 40 percent plugging, respectively. With the moreconcentrated pretreatment, the fruit was too loose to pull at 500 and700 ppm., while the average pull required was 6.4 and 7.3 pounds at the100 and 300 ppm. rates. The only plugging noted was 20 percent at thelowest application rate.

EXAMPLE V rates, and the average pull required at 500 ppm. was 8.5pounds. The treated fruit was too loose to pull at 750 and 1,000 ppm,and all of the treated fruit had fallen .to the ground at the twohighest rates. Fruit burn and leaf drop at the highest rate wassignificantly reduced at the lower rates.

While the invention has been described herein with regard to certainrepresentative examples for purpose of illustrating its practice, it isnot to be construed as limited thereto. Those skilled in the art willreadily recognize the variations and modifications which can be madewithout departing from the spirit and scope of this invention.

What is claimed is:

l. A method for facilitating the harvest of fruit which comprisesapplying an effective concentration of p-isothiocyanatophenylacetic acidto fruit bearing trees within 2 weeks of the date of harvest.

2. A method as defined in claim 1 wherein applica tion is at aconcentration of 100 to 4,000 ppm.

3. A method as defined in claim 1 wherein application is at least 3 or 4days prior to the date of harvest.

4. a method as defined in claim 1 wherein the fruit are citrus orolives.

5. A method as defined in claim 4 wherein the fruit are citrus.

6. A method as defined in claim 1 wherein application is at aconcentration of 500 to 2,000 ppm. and is at least 3 or 4 days prior to'the date of harvest.

7. A method as defined in claim 6 wherein the fruit are citrus orolives.

8. A method as defined in claim 7 wherein the fruit are citrus.

9. A method as defined in claim I wherein application is at aconcentration of 500 to 2,000 ppm. and the fruit are citrus or olives.

10. A method as defined in claim 9 wherein the fruit are citrus.

1. A METHOD FOR FACILITATING THE HARVEST OF FRUIT WHICH COMPRISESAPPLYING AN EFFECTIVE CONCENTRATION OF PISOTHIOCYANATOPHENYLACETIC ACIDTO FRUIT BEARING TREES WITHIN 2 WEEKS OF THE DATE OF HARVESTo
 2. Amethod as defined in claim 1 wherein application is at a concentrationof 100 to 4,000 ppm.
 3. A method as defined in claim 1 whereinapplication is at least 3 or 4 days prior to the date of harvest.
 4. amethod as defined in claim 1 wherein the fruit are citrus or olives. 5.A method as defined in claim 4 wherein the fruit are citrus.
 6. A methodas defined in claim 1 wherein application is at a concentration of 500to 2,000 ppm. and is at least 3 or 4 days prior to the date of harvest.7. A method as defined in claim 6 wherein the fruit are citrus orolives.
 8. A method as defined in claim 7 wherein the fruit are citrus.9. A method as defined in claim 1 wherein application is at aconcentration of 500 to 2,000 ppm. and the fruit are citrus or olives.10. A method as defined in claim 9 wherein the fruit are citrus.